Production of pure iron



Patented May 20, 1930 UNITED STATES PATENT OFFICE ALWIN MITTASCH, AND CARL MNLLER, OF MANN HEIM, AND EDUARD LINC'KH, OF LUD- WIGSHAFEN-ON-THE-RHINE, GERMANY, ASSIGNORS TO I. G. FARBENINDUSTRIE AK- TIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN, GERMANY, A CORPORATION 01' GERILANY Io Drawing. Application filed July 2, 1927, Serial No. 203,258, and in Germany July 5, 1926.

It is known that pure iron can be produced from iron carbonyl by thermal decomposition by passing the iron carbonyl, in a vaporous and diluted condition, that is in the presence of inert or reducing gases or under diminished pressure, through heated liquids or melts. v

We have now found that it is not essential to employ the iron carbonyl in a diluted con dition, but that it is often preferable to bring it in an undiluted liquid or vaporous condition into contact wth the hot liquid" or melt. If, for example, the decomposition be effected by introducing iron carbonyl into molten iron, the method according to the present invention is preferable to employing a' gas which dilutes the carbonyl vapor, since such gas extracts considerable quantities of heat in its passage through the melt The decomposition of the iron carbonyl can be carried out for example by passing the liquid or vaporous carbonyl throu h the heated liquid or melt at ordnary or un er increased pressure, or by bringing it, in the form of vapor, into contact with the surface of a suitably agitated liquid or melt, or by spraying or dropping it, in the liquid condition, onto the liquid.

The working temperatures generally employed are between 100 and ,400" C or above 1000 C. in order to prevent extensive deposition of carbon as the result of the decomposition ofcarbon monoxid at the intermediate range of temperature. If, however, it is desired to obtain an iron possessing acertain high content of carbon or iron carbide, the decomposition is efi'ected'at temperatures between 400 and 1000 C Organic liquids of high boiling point, such as paraffin oils and the like, have been found suitable substances for the decomposition process. Substances of lower boiling point may also be used, provided the operation be carried out in closed vessels under pressure. The decomposition may also be effected with the aid of melts of salts or metals, in which case, according to the nature of the melt, the resulting iron is deposited either in the form of a fine powder, as when heated liquids are used, or is dissolved in the melt as, for ex ample, when the decomposition is eifected in molten iron, the metal being then produced directly in a pure, compact state.

The process according to the present in- "ention hasthe advantage that no gas is required for diluting the carbonyl, for which purposeno industrial gas can generally be employed, as such diluting gas must be dry and free from oxidizing constituents, so that it 1s rather expensive to produce. Moreover, by the absence of a diluting as a considera ly smaller supply of heat is necessary, as no gas mustbe heated together with the carbonyl. Further, in the present process pure carbon monoxid is recovered while in the operation with diluted iron carbonyl the carbon monoxid is strongly diluted with other gasesand therefore not suitable for all industrial purposes, unless pure carbon monoxid itself be employed as diluting gas.

The following example will further illustrate how the invention may be carried out in practice but the invention is not restricted thereto.

Ewample set our hands.

ALWIN MITTASCH. CARL MULLER. EDUARD. LINOKH. 

